Answer:
It will take 7 hours for car B to catch up to Car A.
Explanation:
So if you write the the two equations out:
You'll want to assume that x is how many hours and y is how many km.
The reason car B has, -140, is because car A is in front of it by two hours and in those two hours it reached 140km. Meaning that Car B is starting at 140 km behind Car A.
If you graph these two equations out you'll realize that they intersect at the point (7, 490). Meaning that Car B caught up with Car A after 7 hours and both cars had traveled 490km.